1. Field of the Invention
The invention relates to the assembly of an electrodynamic fractionating unit (FRANKA=Fraktionieranlage Karlsruhe), used for fragmenting, grinding, or suspending a brittle mineral material to be processed.
2. Related Art
All presently known units of this type, developed for the processing of mineral materials by means of fragmenting, material removal, drilling or similar processing methods, in particular the electrodynamic method, with the aid of high-power, high-voltage discharges, comprise the following main components:
The energy store, meaning the unit for generating a high-voltage (HV) pulse, which frequently or in most cases is a Marx generator known from the field of high-voltage pulse technology, and the application-specific reaction/process vessel filled with a process fluid. The exposed end region of a high-voltage electrode which is connected to the energy store is completely submerged into this fluid. The electrode at reference potential is arranged opposite the high-voltage electrode and, in most cases, is a correspondingly designed bottom of the reaction vessel which functions as earth electrode. If the amplitude of the high-voltage pulse at the high-voltage electrode reaches a sufficiently high value, an electric arc-over occurs from the high-voltage electrode to the earth electrode. Depending on the prevailing geometric conditions and the form, particularly the rise time for the high-voltage pulse, the arc-over travels through the fragmentation material positioned between the electrodes and is thus highly effective. An arc-over which travels only through the process fluid at best can only generate shock waves, which are not very effective.
For the duration of the high-voltage pulse, the electrical circuit is formed by the energy store C with thereto connected high-voltage electrode, the space between the high-voltage electrode and the bottom of the reaction vessel, and the return-flow line from the vessel bottom to the energy store. This circuit comprises the capacitive, ohmic, and inductive components C, R and L, which influence the form of the high-voltage pulse (see FIG. 6), meaning the speed at which it rises as well as the further chronological course of the discharge current and thus also the pulse power introduced into the load and, as a result, the efficiency of the discharge with respect to the material fragmentation. For the discharge current pulse interval, the electrical energy amount Ri2 is converted to heat in the ohmic resistance R of this temporary circuit. This energy amount consequently is no longer available for the actual fractionating operation.
This circuit represents a conductor loop through which extremely high currents of approximately 2-5 kA flow during an extremely short interval. A configuration of this type generates intensive electromagnetic radiation, meaning it represents a radio transmitter with high radiation capacity, which must be screened with the aid of expensive technology to avoid causing interference in the technical environment. In general, a unit of this type must be screened with the aid of protective devices in such a way that no contact with live, current-carrying components is possible during the operation. In turn, this quickly leads to extensive protective installations over and above the actual assembly for use.
All units known so far, which operate based on the electrodynamic method, have an open design, meaning the components of such a unit are connected to each other by electrical lines (see FIG. 6).
For the fragmenting of rock-type material, for example as described in reference WO 96/26 010, connecting lines between the electric energy store and the spark gap are visible, which form current-carrying loops during the discharge of the HV pulse. Material removal systems (DE 197 36 027 C2), systems for drilling in solid rock (U.S. Pat. No. 6,164,388), or inerting systems (DE 199 02 010 C2) respectively show simple electrical lines that are connected to the high-voltage electrode.